In recent years, there is a demand for technical innovation for CO2 reduction in relation to the phenomenon of global warming, and attention has been paid to new energy utilization technologies for suppressing the amount of use of energy resources. One of the candidate technologies is a technology involving the use of natural energy such as sunlight and wind power as energy sources, and another promising candidate technology is a technology of reutilizing the loss of energy resources.
Under the current circumstances of energy utilization, about 60% of primary energy is dissipated as heat, and thus it is required to reutilize this industrial waste heat as electric power. Regarding the technology for converting waste heat to electric power, a conversion technology of using a turbine is generally used. However, in a region with a low heat density or in a region where it is spatially difficult to design a turbine, conversion technologies of using a thermoelectric conversion module that utilizes the Seebeck effect have been suggested.
In the thermoelectric conversion technologies, thermoelectric conversion modules that include thermoelectric conversion materials are used. Furthermore, among the thermoelectric conversion materials, as thermoelectric conversion materials having temperature characteristics that are applicable to waste heat recovery at 200° C. or lower, full Heusler alloys are used.
JP 2013-89882 A (PTL 1) discloses that when the chemical composition ratio of Fe and V in the basic structure of Fe2VAl is adjusted to an adjustment amount within a particular range, and some of the constituent elements are substituted with other elements, the absolute value of the Seebeck coefficient can be increased.
WO 2013/175571 A1 (PTL 2) discloses that the material of a thermoelectric conversion unit included in a thermoelectric conversion module includes Fe, Ti, and at least any one of Si and Sn.
NPL 1 describes the thermoelectric conversion characteristics of a Fe2TiAl Heusler alloy. Also, NPL 2 describes the structures and mechanical characteristics of Fe—Al—Ti alloys, and it is described therein that Fe—Al—Ti alloys exhibit a microstructure that includes Fe2TiAl, depending on the composition.